This invention relates to a cylinder head gasket interposed between a cylinder head and a cylinder block, particularly to a cylinder head gasket in which plural thin metal plates are laminated.
In the prior art, as a cylinder head gasket to be interposed between a cylinder head and a cylinder block, there have been known various cylinder head gaskets using a single thin metal plate or plural thin metal plates as shown in FIG. 4 to FIG. 6.
In known cylinder head gasket in which plural thin metal plates are laminated as shown in FIG. 4 and FIG. 5, the total height of the cylinder head gasket can be regulated by the number of thin plates thereof, and a member for heightening sealing property at combustion room bores and fluid bores piercing the gasket can be provided extremely easily at said bores, whereby the gasket has excellent advantages as compared with a cylinder head gasket constituted by a single thin plate described above.
Moreover, in the case where a coating layer of a rubber type or resin type material is provided on the contacting surface of the above gasket in which thin plates are laminated, the gasket has an advantage that when contact pressure with a high load is applied to the laminated thin plates, the laminated thin plates can be deformed by compression because of this coating layer and can be also conformed easily to deformation of a cylinder head or a cylinder block.
For the purpose of preventing fretting and also for the purpose of improving microsealing property, a coating layer is formed not only on the above contacting surface but also on the surface of a thin plate to be contacted with a cylinder head or a cylinder block.
As such a gasket in which thin metal plates are laminated, there has been known a gasket in which coating layers 12 of a rubber type material are provided on the surfaces of laminated thin plates 10 and 11 and on the contacting surface thereof (FIG. 4); or a gasket in which a coating layer is not provided on the contacting surfaces of laminated thin plates 13 to 18, the thin plates 13 to 18 are merely laminated, and a coating layer 19 of a resin type material is provided only on the surface of the outermost thin plate 13 (FIG. 5).
However, when a rubber type material is used for a coating layer, if contact pressure with a high load is applied to, flow breaking or peeling of a coating layer occurs. When a resin type material is used for a coating layer, there are problems that from the standpoint of productivity, it is difficult to form a coating layer so as to have a desired thickness and a creep phenomenon is caused easily by thermal influence. Further, when a coating layer is not applied to the contacting surface of a gasket in which thin plates are laminated, there is a problem that the thin plates do not conform to the deformations of a cylinder head or cylinder block, and therefore such a laminate cannot function as a gasket therefore.
On the other hand, in the prior art, there has been known a gasket in which a composite material, i.e., a material comprising a rubber material, a filler, an organic fiber, an inorganic fiber and the like, is used in place of a rubber type or resin type material to be used for the above coating layer. In the gasket, a coating layer is constituted by such a composite material, and as shown in FIG. 6, coating layers 21 of the composite material are provided on both surfaces of a single thin plate 20.
This gasket has mechanical strength and durability against flow breaking, peeling or creep. However, the gasket does not comprise laminated thin plates so that it does not have the above excellent advantages which can be obtained by lamination.